A sheet-fed rotary press printer for printing a sheet of paper on its front and back sides in a plurality of colors is disclosed in JP H11-277718 A.
In this printing machine, a plurality of first printing units is succeeded by a plurality of second printing units via a turnover unit so that a sheet of paper may be printed on its front side in colors by the first printing units, be turned over and be printed on its back side in colors by the second printing units.
An electrophotographic printer for printing a sheet of paper on its front and back sides is disclosed in JP 2012-068375 A.
In this printing machine, a first and a second impression cylinder are brought into rotational contact with each other and have a first and a second transfer roller of an electrophotographic printing unit brought into rotational contact therewith, respectively. A sheet of paper is passed through a region of rotational contact between the first impression cylinder and transfer roller to print on the front side and is passed through a region of rotational contact between the second impression cylinder and transfer roller to print on the back side.
The former printing machine as it needs to be equipped with the first and second printing units requires a large area on which it is installed, and increase the cost of equipment.
Especially for multicolor printing, the need for a plurality of the first printing units and a plurality of the second printing units requires larger area of the installation and further increases the equipment cost.
The latter printing machine needed to include the first and second impression cylinders requires an increased area of its installation.
Made to solve the problems mentioned above, the present invention seeks to provide an electrophotographic sheet-fed front and back printing machine which is capable of printing a sheet of paper on its front and back sides and which can be installed in a reduced space.